of: Add of_phandle_args_equal() helper

Add a helper comparing two "struct of_phandle_args" to avoid
reinventing the wheel.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240129115216.96479-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Author: krzk

include/linux/of.h

@@ -1065,6 +1065,22 @@ static inline int of_parse_phandle_with_optional_args(const struct device_node *
 					    0, index, out_args);
 }
 
+/**
+ * of_phandle_args_equal() - Compare two of_phandle_args
+ * @a1:		First of_phandle_args to compare
+ * @a2:		Second of_phandle_args to compare
+ *
+ * Return: True if a1 and a2 are the same (same node pointer, same phandle
+ * args), false otherwise.
+ */
+static inline bool of_phandle_args_equal(const struct of_phandle_args *a1,
+					 const struct of_phandle_args *a2)
+{
+	return a1->np == a2->np &&
+	       a1->args_count == a2->args_count &&
+	       !memcmp(a1->args, a2->args, sizeof(a1->args[0]) * a1->args_count);
+}
+
 /**
  * of_property_count_u8_elems - Count the number of u8 elements in a property
  *